while adding/removing ATF to get the level just right, I noticed something quite strange. When I added more fluid to get it to max level, the engine idle rpm would jump up & down constantly from 450 to 700?? this effect was more prominant when I put the gear in D.

then when i pulled out about a half quart, the RPM fluctuation got a lot better. Am I imagining things here, or is there a reason for this??

car=97 E420, trans=722.6